The mineral covellite, typically indigo blue to dark blue in color, often displays iridescence that is purplish to deep red. When present in quartz, it exhibits a glittering appearance not soon forgotten. Covellite was named in honor of Niccolo Covelli, an Italian mineralogist who discovered the mineral at Mount Vesuvius.

Colors

Colorless With Metallic Blue, Blue-Black Sometimes With Iridescence

Covellite In Quartz Classification

Common Name

Covellite In Quartz

Species

Quartz

Variety

Covellite In Quartz

Colors

Colorless With Metallic Blue, Blue-Black Sometimes With Iridescence

Alternate Names

Gemstone Groups

Key Separations

Refractive index, appearance, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz; may also show Airy's spiral optic figure and Brazil-law twinning under crossed polarizing filters.

Comments

Covellite In Quartz Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.544-1.553 Tolerance:very constant

Birefringence

0.009

Optic Character

Optic Sign

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Strength: weak fire Value: 0.013

Comments

Covellite In Quartz Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Tetragonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline to Aggregate

Comments

Covellite In Quartz Characteristic Physical Properties

Hardness

7

Streak

White

Specific Gravity

2.64-2.69 Typical:2.66

Toughness

Good

Inclusions

Covellite in quartz will have covellite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.